diff --git a/CHANGELOG.md b/CHANGELOG.md
index e63c7b9..351ac82 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,54 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+## [3.2.0] - 2026-01-14
+
+### Added
+- **guide/data-privacy.md** - Comprehensive data privacy documentation (NEW, ~200 lines)
+  - TL;DR retention table: 5 years (default) | 30 days (opt-out) | 0 (Enterprise ZDR)
+  - Data flow diagram showing what leaves your machine
+  - Known risks with MCP database connections
+  - Protection measures (excludePatterns, hooks, MCP safety)
+  - Quick checklist for immediate action
+
+- **README.md** - Privacy notice encart (3 lines after transparency note)
+  - Retention summary with action link
+  - Direct link to opt-out and full guide
+
+- **guide/ultimate-guide.md** - Section 2.6 "Data Flow & Privacy" (~45 lines)
+  - Data types sent table
+  - Retention policies table
+  - Link to dedicated guide
+  - Updated TOC and quick jump navigation
+
+- **tools/onboarding-prompt.md** - Phase 0.5 Privacy Awareness
+  - Privacy notice shown after level assessment
+  - Asks user about privacy settings configuration
+
+- **tools/audit-prompt.md** - Privacy configuration checks
+  - Phase 1.2: PRIVACY CONFIGURATION bash checks
+  - Phase 2.1: Privacy Configuration checklist
+  - Glossary: "Data Retention" and "excludePatterns" terms
+
+- **examples/scripts/audit-scan.sh** - PRIVACY CHECK section
+  - Human output: .env exclusion check, DB MCP warning, opt-out link
+  - JSON output: `"privacy"` object with env_excluded, has_db_mcp, opt_out_link, guide_link
+
+- **examples/scripts/check-claude.sh** - Privacy reminder section
+  - Shows retention info and opt-out link during health check
+
+- **examples/hooks/bash/privacy-warning.sh** - SessionStart hook (NEW)
+  - Displays privacy reminder box once per terminal session
+  - Suppresses with `PRIVACY_WARNING_SHOWN=1` env var
+
+- **guide/cheatsheet.md** - Golden Rule #7 added
+  - "Know what's sent — prompts, files, MCP results → Anthropic"
+
+### Stats
+- 2 new files created (data-privacy.md, privacy-warning.sh)
+- 8 files modified (README, guide, cheatsheet, audit-scan, check-claude, onboarding, audit-prompt)
+- Focus on user awareness of data retention and actionable opt-out
+
 ## [3.1.0] - 2026-01-13
 
 ### Changed
diff --git a/README.md b/README.md
index f2b1a00..130a684 100644
--- a/README.md
+++ b/README.md
@@ -10,6 +10,12 @@
 
 ---
 
+> **Privacy Notice**: Claude Code sends your prompts, file contents, and MCP results to Anthropic servers.
+> - **Default**: 5 years retention (training enabled) | **Opt-out**: 30 days | **Enterprise**: 0
+> - **Action**: [Disable training](https://claude.ai/settings/data-privacy-controls) | [Full privacy guide](./guide/data-privacy.md)
+
+---
+
 **Start here:**
 - [Cheat Sheet](./guide/cheatsheet.md) — print this, start coding
 - [15-min Quick Start](./guide/ultimate-guide.md#1-quick-start-day-1) — first workflow
diff --git a/examples/hooks/bash/privacy-warning.sh b/examples/hooks/bash/privacy-warning.sh
new file mode 100644
index 0000000..5128b80
--- /dev/null
+++ b/examples/hooks/bash/privacy-warning.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+# privacy-warning.sh - Warn users about data sent to Anthropic
+#
+# Hook type: SessionStart
+# Triggers: Once at the beginning of each Claude Code session
+#
+# Purpose:
+#   Reminds users that their prompts, files, and MCP results are sent to Anthropic.
+#   Provides link to opt-out of training data (reduces retention from 5 years to 30 days).
+#
+# Installation:
+#   1. Copy to .claude/hooks/SessionStart/
+#   2. Make executable: chmod +x privacy-warning.sh
+#   3. Register in hooks config (see Claude Code docs)
+#
+# Configuration:
+#   Set PRIVACY_WARNING_SHOWN=1 in your environment to suppress after first run.
+#
+# Reference: https://github.com/FlorianBruniaux/claude-code-ultimate-guide/blob/main/guide/data-privacy.md
+
+# Only show once per terminal session
+if [[ -n "$PRIVACY_WARNING_SHOWN" ]]; then
+    exit 0
+fi
+
+# Output privacy reminder
+echo ""
+echo "┌─────────────────────────────────────────────────────────────────┐"
+echo "│  🔐 PRIVACY REMINDER                                           │"
+echo "├─────────────────────────────────────────────────────────────────┤"
+echo "│  Your prompts, files, and MCP results are sent to Anthropic.   │"
+echo "│                                                                 │"
+echo "│  Retention: 5 years (default) → 30 days (opt-out training)     │"
+echo "│                                                                 │"
+echo "│  Disable training: claude.ai/settings/data-privacy-controls    │"
+echo "└─────────────────────────────────────────────────────────────────┘"
+echo ""
+
+# Mark as shown for this terminal session
+export PRIVACY_WARNING_SHOWN=1
+
+# Always exit 0 to allow session to continue
+exit 0
diff --git a/examples/scripts/audit-scan.sh b/examples/scripts/audit-scan.sh
index 7d82de6..67e71da 100755
--- a/examples/scripts/audit-scan.sh
+++ b/examples/scripts/audit-scan.sh
@@ -588,6 +588,12 @@ if [[ "$OUTPUT_MODE" == "json" ]]; then
     "claude_md_lines": $CLAUDE_MD_LINES,
     "claude_md_refs": $CLAUDE_MD_REFS
   },
+  "privacy": {
+    "env_excluded": $([ -f "./.claude/settings.json" ] && grep -q '\.env' "./.claude/settings.json" 2>/dev/null && echo "true" || echo "false"),
+    "has_db_mcp": $(echo "$MCP_ALL_SERVERS" | grep -qiE "postgres|neon|supabase|mysql|database" 2>/dev/null && echo "true" || echo "false"),
+    "opt_out_link": "https://claude.ai/settings/data-privacy-controls",
+    "guide_link": "guide/data-privacy.md"
+  },
   "mcp": {
     "configured": $([ -n "$MCP_SERVERS" ] && echo "true" || echo "false"),
     "count": $MCP_COUNT,
@@ -649,6 +655,24 @@ else
     fi
   fi
 
+  echo -e "\n${BLUE}🔐 PRIVACY CHECK${NC}"
+  # Check excludePatterns for sensitive files
+  HAS_ENV_EXCLUSION="false"
+  if [[ -f "./.claude/settings.json" ]]; then
+    grep -q '\.env' "./.claude/settings.json" 2>/dev/null && HAS_ENV_EXCLUSION="true"
+  fi
+
+  [[ "$HAS_ENV_EXCLUSION" == "true" ]] && echo -e "  ${GREEN}✅${NC} .env excluded in settings" || echo -e "  ${RED}⚠️${NC}  .env NOT excluded (add to excludePatterns)"
+
+  # Check for database MCP servers (production risk)
+  if echo "$MCP_ALL_SERVERS" | grep -qiE "postgres|neon|supabase|mysql|database" 2>/dev/null; then
+    echo -e "  ${YELLOW}⚠️${NC}  Database MCP detected → ensure NOT production data"
+  fi
+
+  # Privacy reminders
+  echo -e "  ${CYAN}💡${NC} Opt-out training: https://claude.ai/settings/data-privacy-controls"
+  echo -e "  ${CYAN}💡${NC} Full guide: guide/data-privacy.md"
+
   echo -e "\n${BLUE}🔌 MCP SERVERS${NC}"
   if [[ -n "$MCP_ALL_SERVERS" ]]; then
     echo -e "  ${GREEN}✅${NC} Configured ($MCP_COUNT total): $MCP_ALL_SERVERS"
diff --git a/examples/scripts/check-claude.sh b/examples/scripts/check-claude.sh
index b38175a..2ae77ef 100644
--- a/examples/scripts/check-claude.sh
+++ b/examples/scripts/check-claude.sh
@@ -26,6 +26,11 @@ else
     echo "✗ ANTHROPIC_API_KEY not set"
 fi
 
+echo -e "\n--- Privacy Reminder ---"
+echo "⚠️  Your prompts and file contents are sent to Anthropic"
+echo "   Default retention: 5 years (training) | Opt-out: 30 days"
+echo "   → Disable training: https://claude.ai/settings/data-privacy-controls"
+
 echo -e "\n--- MCP Servers ---"
 claude mcp list
 
diff --git a/guide/cheatsheet.md b/guide/cheatsheet.md
index a06de83..cfbcee5 100644
--- a/guide/cheatsheet.md
+++ b/guide/cheatsheet.md
@@ -6,7 +6,7 @@
 
 **Written with**: Claude (Anthropic)
 
-**Version**: 3.1.0 | **Last Updated**: January 2026
+**Version**: 3.2.0 | **Last Updated**: January 2026
 
 ---
 
@@ -314,6 +314,7 @@ claude -p "fix typos" --dangerously-skip-permissions
 4. **Plan Mode first** for complex/risky tasks
 5. **Create CLAUDE.md** for every project
 6. **Commit frequently** after each completed task
+7. **Know what's sent** — prompts, files, MCP results → Anthropic ([opt-out training](https://claude.ai/settings/data-privacy-controls))
 
 ---
 
@@ -378,4 +379,4 @@ where.exe claude; claude doctor; claude mcp list
 
 **Author**: Florian BRUNIAUX | [@Méthode Aristote](https://methode-aristote.fr) | Written with Claude
 
-*Last updated: January 2026 | Version 3.0.7*
+*Last updated: January 2026 | Version 3.2.0*
diff --git a/guide/data-privacy.md b/guide/data-privacy.md
new file mode 100644
index 0000000..8aeb38c
--- /dev/null
+++ b/guide/data-privacy.md
@@ -0,0 +1,289 @@
+# Data Privacy & Retention Guide
+
+> **Critical**: Everything you share with Claude Code is sent to Anthropic servers. This guide explains what data leaves your machine and how to protect sensitive information.
+
+## TL;DR - Retention Summary
+
+| Configuration | Retention Period | Training | How to Enable |
+|---------------|------------------|----------|---------------|
+| **Default** | 5 years | Yes | (default state) |
+| **Opt-out** | 30 days | No | [claude.ai/settings](https://claude.ai/settings/data-privacy-controls) |
+| **Enterprise (ZDR)** | 0 days | No | Enterprise contract |
+
+**Immediate action**: [Disable training data usage](https://claude.ai/settings/data-privacy-controls) to reduce retention from 5 years to 30 days.
+
+---
+
+## 1. Understanding the Data Flow
+
+### What Leaves Your Machine
+
+When you use Claude Code, the following data is sent to Anthropic:
+
+```
+┌─────────────────────────────────────────────────────────────┐
+│                    YOUR LOCAL MACHINE                       │
+├─────────────────────────────────────────────────────────────┤
+│  • Prompts you type                                         │
+│  • Files Claude reads (including .env if not excluded!)     │
+│  • MCP server results (SQL queries, API responses)          │
+│  • Bash command outputs                                     │
+│  • Error messages and stack traces                          │
+└───────────────────────┬─────────────────────────────────────┘
+                        │
+                        ▼ HTTPS
+┌─────────────────────────────────────────────────────────────┐
+│                    ANTHROPIC API                            │
+├─────────────────────────────────────────────────────────────┤
+│  • Processes your request                                   │
+│  • Stores conversation based on retention policy            │
+│  • May use data for model training (if not opted out)       │
+└─────────────────────────────────────────────────────────────┘
+```
+
+### What This Means in Practice
+
+| Scenario | Data Sent to Anthropic |
+|----------|------------------------|
+| You ask Claude to read `src/app.ts` | Full file contents |
+| You run `git status` via Claude | Command output |
+| MCP executes `SELECT * FROM users` | Query results with user data |
+| Claude reads `.env` file | API keys, passwords, secrets |
+| Error occurs in your code | Full stack trace with paths |
+
+---
+
+## 2. Anthropic Retention Policies
+
+### Tier 1: Default (Training Enabled)
+
+- **Retention**: 5 years
+- **Usage**: Model improvement, training data
+- **Applies to**: Free, Pro, Max plans without opt-out
+
+### Tier 2: Training Disabled (Opt-Out)
+
+- **Retention**: 30 days
+- **Usage**: Safety monitoring, abuse prevention only
+- **How to enable**:
+  1. Go to https://claude.ai/settings/data-privacy-controls
+  2. Disable "Allow model training on your conversations"
+  3. Changes apply immediately
+
+### Tier 3: Enterprise API (Zero Data Retention)
+
+- **Retention**: 0 days (real-time processing only)
+- **Usage**: None - data not stored
+- **Requires**: Enterprise contract with Anthropic
+- **Use cases**: HIPAA, GDPR, PCI-DSS compliance, government contracts
+
+---
+
+## 3. Known Risks
+
+### Risk 1: Automatic File Reading
+
+Claude Code reads files to understand context. By default, this includes:
+
+- `.env` and `.env.local` files (API keys, passwords)
+- `credentials.json`, `secrets.yaml` (service accounts)
+- SSH keys if in workspace scope
+- Database connection strings
+
+**Mitigation**: Configure `excludePatterns` (see Section 4).
+
+### Risk 2: MCP Database Access
+
+When you configure database MCP servers (Neon, Supabase, PlanetScale):
+
+```
+Your Query: "Show me recent orders"
+            ↓
+MCP Executes: SELECT * FROM orders LIMIT 100
+            ↓
+Results Sent: 100 rows with customer names, emails, addresses
+            ↓
+Stored at Anthropic: According to your retention tier
+```
+
+**Mitigation**: Never connect production databases. Use dev/staging with anonymized data.
+
+### Risk 3: Shell Command Output
+
+Bash commands and their output are included in context:
+
+```bash
+# This output goes to Anthropic:
+$ env | grep API
+OPENAI_API_KEY=sk-abc123...
+STRIPE_SECRET_KEY=sk_live_...
+```
+
+**Mitigation**: Use hooks to filter sensitive command outputs.
+
+### Risk 4: Documented Community Incidents
+
+| Incident | Source |
+|----------|--------|
+| Claude reads `.env` by default | r/ClaudeAI, GitHub issues |
+| DROP TABLE attempts on poorly configured MCP | r/ClaudeAI |
+| Credentials exposed via environment variables | GitHub issues |
+| Prompt injection via malicious MCP servers | r/programming |
+
+---
+
+## 4. Protective Measures
+
+### Immediate Actions
+
+#### 4.1 Opt-Out of Training
+
+1. Visit https://claude.ai/settings/data-privacy-controls
+2. Toggle OFF "Allow model training"
+3. Retention reduces from 5 years to 30 days
+
+#### 4.2 Configure File Exclusions
+
+In `.claude/settings.json`:
+
+```json
+{
+  "excludePatterns": [
+    ".env",
+    ".env.*",
+    "**/.env",
+    "**/.env.*",
+    "**/credentials*",
+    "**/secrets*",
+    "**/*.pem",
+    "**/*.key",
+    "**/service-account*.json"
+  ]
+}
+```
+
+Or create `.claudeignore` in project root:
+
+```gitignore
+# Secrets
+.env
+.env.*
+*.pem
+*.key
+credentials.json
+secrets/
+
+# Sensitive configs
+**/config/production.*
+```
+
+#### 4.3 Use Security Hooks
+
+Create `.claude/hooks/PreToolUse.sh`:
+
+```bash
+#!/bin/bash
+INPUT=$(cat)
+TOOL_NAME=$(echo "$INPUT" | jq -r '.tool.name')
+
+if [[ "$TOOL_NAME" == "Read" ]]; then
+    FILE_PATH=$(echo "$INPUT" | jq -r '.tool.input.file_path')
+
+    # Block reading sensitive files
+    if [[ "$FILE_PATH" =~ \.env|credentials|secrets|\.pem|\.key ]]; then
+        echo "BLOCKED: Attempted to read sensitive file: $FILE_PATH" >&2
+        exit 2  # Block the operation
+    fi
+fi
+```
+
+### MCP Best Practices
+
+| Rule | Rationale |
+|------|-----------|
+| **Never connect production databases** | All query results sent to Anthropic |
+| **Use read-only database users** | Prevents DROP/DELETE/UPDATE accidents |
+| **Anonymize development data** | Reduces PII exposure risk |
+| **Create minimal test datasets** | Less data = less risk |
+| **Audit MCP server sources** | Third-party MCPs may have vulnerabilities |
+
+### For Teams
+
+| Environment | Recommendation |
+|-------------|----------------|
+| **Development** | Opt-out + exclusions + anonymized data |
+| **Staging** | Consider Enterprise API if handling real data |
+| **Production** | NEVER connect Claude Code directly |
+
+---
+
+## 5. Comparison with Other Tools
+
+| Feature | Claude Code + MCP | Cursor | GitHub Copilot |
+|---------|-------------------|--------|----------------|
+| Data scope sent | Full SQL results, files | Code snippets | Code snippets |
+| Production DB access | Yes (via MCP) | Limited | Not designed for |
+| Default retention | 5 years | Variable | 30 days |
+| Training by default | Yes | Opt-in | Opt-in |
+
+**Key difference**: MCP creates a unique attack surface because MCP servers are separate processes with independent network/filesystem access.
+
+---
+
+## 6. Enterprise Considerations
+
+### When to Use Enterprise API (ZDR)
+
+- Handling PII (names, emails, addresses)
+- Regulated industries (HIPAA, GDPR, PCI-DSS)
+- Client data processing
+- Government contracts
+- Financial services
+
+### Evaluation Checklist
+
+- [ ] Data classification policy exists for your organization
+- [ ] API tier matches data sensitivity requirements
+- [ ] Team trained on privacy controls
+- [ ] Incident response plan for potential data exposure
+- [ ] Legal/compliance review completed
+
+---
+
+## 7. Quick Reference
+
+### Links
+
+| Resource | URL |
+|----------|-----|
+| Privacy settings | https://claude.ai/settings/data-privacy-controls |
+| Anthropic usage policy | https://www.anthropic.com/policies |
+| Enterprise information | https://www.anthropic.com/enterprise |
+| Terms of service | https://www.anthropic.com/legal/consumer-terms |
+
+### Commands
+
+```bash
+# Check current Claude config
+claude /config
+
+# Verify exclusions are loaded
+claude /status
+
+# Run privacy audit
+./examples/scripts/audit-scan.sh
+```
+
+### Quick Checklist
+
+- [ ] Training opt-out enabled at claude.ai/settings
+- [ ] `.env*` files in excludePatterns or .claudeignore
+- [ ] No production database connections via MCP
+- [ ] Security hooks installed for sensitive file access
+- [ ] Team aware of data flow to Anthropic
+
+---
+
+## Changelog
+
+- 2026-01: Initial version - documenting retention policies and protective measures
diff --git a/guide/ultimate-guide.md b/guide/ultimate-guide.md
index fb93b99..44e9424 100644
--- a/guide/ultimate-guide.md
+++ b/guide/ultimate-guide.md
@@ -10,7 +10,7 @@
 
 **Last updated**: January 2026
 
-**Version**: 3.1.0
+**Version**: 3.2.0
 
 ---
 
@@ -112,6 +112,7 @@ Context full → /compact or /clear
   - [2.3 Plan Mode](#23-plan-mode)
   - [2.4 Rewind](#24-rewind)
   - [2.5 Mental Model](#25-mental-model)
+  - [2.6 Data Flow & Privacy](#26-data-flow--privacy)
 - [3. Memory & Settings](#3-memory--settings)
   - [3.1 Memory Files (CLAUDE.md)](#31-memory-files-claudemd)
   - [3.2 The .claude/ Folder Structure](#32-the-claude-folder-structure)
@@ -875,7 +876,7 @@ Keep Copilot/Cursor for:
 
 # 2. Core Concepts
 
-_Quick jump:_ [The Interaction Loop](#21-the-interaction-loop) · [Context Management](#22-context-management) · [Plan Mode](#23-plan-mode) · [Rewind](#24-rewind) · [Mental Model](#25-mental-model)
+_Quick jump:_ [The Interaction Loop](#21-the-interaction-loop) · [Context Management](#22-context-management) · [Plan Mode](#23-plan-mode) · [Rewind](#24-rewind) · [Mental Model](#25-mental-model) · [Data Flow & Privacy](#26-data-flow--privacy)
 
 ---
 
@@ -2211,6 +2212,48 @@ cat claudedocs/templates/code-review.xml | \
 
 > **Source**: [DeepTo Claude Code Guide - XML-Structured Prompts](https://cc.deeptoai.com/docs/en/best-practices/claude-code-comprehensive-guide)
 
+## 2.6 Data Flow & Privacy
+
+> **Important**: Everything you share with Claude Code is sent to Anthropic servers. Understanding this data flow is critical for protecting sensitive information.
+
+### What Gets Sent to Anthropic
+
+When you use Claude Code, the following data leaves your machine:
+
+| Data Type | Example | Risk Level |
+|-----------|---------|------------|
+| Your prompts | "Fix the login bug" | Low |
+| Files Claude reads | `.env`, `src/app.ts` | **High** if contains secrets |
+| MCP query results | SQL query results with user data | **High** if production data |
+| Command outputs | `env \| grep API` output | Medium |
+| Error messages | Stack traces with file paths | Low |
+
+### Retention Policies
+
+| Configuration | Retention | How to Enable |
+|---------------|-----------|---------------|
+| **Default** | 5 years | (default state - training enabled) |
+| **Opt-out** | 30 days | [claude.ai/settings](https://claude.ai/settings/data-privacy-controls) |
+| **Enterprise (ZDR)** | 0 days | Enterprise contract |
+
+**Immediate action**: [Disable training data usage](https://claude.ai/settings/data-privacy-controls) to reduce retention from 5 years to 30 days.
+
+### Protecting Sensitive Data
+
+**1. Exclude sensitive files** in `.claude/settings.json`:
+
+```json
+{
+  "excludePatterns": [".env*", "**/credentials*", "**/*.pem"]
+}
+```
+
+**2. Never connect production databases** to MCP servers. Use dev/staging with anonymized data.
+
+**3. Use security hooks** to block reading of sensitive files (see [Section 7.4](#74-hooks-automating-workflows)).
+
+> **Full guide**: For complete privacy documentation including known risks, community incidents, and enterprise considerations, see [Data Privacy & Retention Guide](./data-privacy.md).
+
 ---
 
 # 3. Memory & Settings
diff --git a/tools/audit-prompt.md b/tools/audit-prompt.md
index 67aca61..010749e 100644
--- a/tools/audit-prompt.md
+++ b/tools/audit-prompt.md
@@ -205,6 +205,29 @@ echo -e "\n=== DOCUMENTATION ==="
 for d in docs/ docs/conventions/ documentation/; do
   [ -d "$d" ] && echo "✅ $d exists"
 done
+
+# Privacy configuration
+echo -e "\n=== PRIVACY CONFIGURATION ==="
+if [ -f "./.claude/settings.json" ]; then
+  if grep -q "\.env" ./.claude/settings.json 2>/dev/null; then
+    echo "✅ .env excluded in settings"
+  else
+    echo "⚠️  .env NOT in excludePatterns"
+  fi
+else
+  echo "⚠️  No settings.json - .env files may be read"
+fi
+
+# Check for database MCP servers (privacy risk)
+if command -v jq &> /dev/null && [ -f ~/.claude.json ]; then
+  DB_MCP=$(jq -r --arg path "$CURRENT_DIR" ".projects[\$path].mcpServers // {} | keys[]" ~/.claude.json 2>/dev/null | grep -iE "postgres|neon|supabase|mysql|database" || true)
+  if [ -n "$DB_MCP" ]; then
+    echo "⚠️  Database MCP detected: $DB_MCP"
+    echo "   → Ensure NOT connected to production data"
+  fi
+fi
+
+echo "💡 Opt-out training: https://claude.ai/settings/data-privacy-controls"
 '
 ```
 
@@ -273,6 +296,12 @@ For each category, evaluate against these criteria based on Phase 1 scan results
 - [ ] Auto-formatting hooks (PostToolUse) if needed
 - [ ] Context enrichment (UserPromptSubmit) if useful
 
+**Privacy Configuration (Guide Section 2.6)**
+- [ ] Training opt-out verified at claude.ai/settings
+- [ ] excludePatterns includes `.env*`, `credentials*`, `*.pem`
+- [ ] MCP database servers NOT connected to production
+- [ ] Team aware data is sent to Anthropic (5 years default, 30 days opt-out)
+
 **MCP Servers (Guide Section 8)**
 - [ ] Serena configured if large codebase (indexation + memory)
 - [ ] Context7 configured if using external libraries
@@ -484,6 +513,8 @@ Here's an example of what the audit report looks like:
 | **Trinity Pattern** | Combining Plan Mode + Think Levels + MCP for complex tasks |
 | **Verify Gate** | CI/CD pattern: build → lint → test → typecheck before merge |
 | **Context Zones** | Green (0-50%), Yellow (50-70%), Red (70%+) - context usage thresholds |
+| **Data Retention** | Anthropic stores conversations: 5 years (default), 30 days (opt-out), 0 days (Enterprise ZDR) |
+| **excludePatterns** | Settings to prevent Claude from reading sensitive files like `.env`, credentials |
 
 ### Priority Levels Explained
 
diff --git a/tools/onboarding-prompt.md b/tools/onboarding-prompt.md
index 5d4723a..0dc4591 100644
--- a/tools/onboarding-prompt.md
+++ b/tools/onboarding-prompt.md
@@ -88,6 +88,24 @@ You are an expert Claude Code instructor. Your mission is to onboard me to Claud
 
 3. **Focus Areas** (optional): Based on my level, you may ask what specific topics interest me most.
 
+### Phase 0.5: Privacy Awareness (CRITICAL)
+
+**After level assessment, inform the user about data privacy:**
+
+⚠️ **Important Privacy Notice** (always show this):
+- Everything you share with Claude Code is sent to Anthropic servers
+- Default retention: **5 years** (training enabled)
+- Opt-out retention: **30 days** (disable training)
+
+**Action required**: [Disable training](https://claude.ai/settings/data-privacy-controls) to reduce retention from 5 years to 30 days.
+
+**Ask**: "Have you configured your privacy settings? Should I explain more about data protection?"
+
+If they want more details, mention:
+- Add `.env*` to excludePatterns
+- Never connect production databases to MCP
+- See [Data Privacy Guide](../guide/data-privacy.md) for full details
+
 ### Phase 1: Read the Guide
 
 **After understanding my preferences, read the guide:**